This invention relates to urological warming devices.
Cryosurgical probes are used to treat a variety of diseases. The cryosurgical probes quickly freeze diseased body tissue, causing the tissue to die after which it will be absorbed by the body, expelled by the body or sloughed off. Cryothermal treatment is currently used to treat prostate cancer and benign prostate disease, breast tumors and breast cancer, liver tumors and liver cancer, glaucoma and other eye diseases. Cryosurgery is also proposed for the treatment of a number of other diseases.
The use of cryosurgical probes for cryoablation of the prostate is described in Onik, Ultrasound-Guided Cryosurgery, Scientific American at 62 (January 1996) and Onik, Cohen, et al., Transrectal Ultrasound-Guided Percutaneous Radial Cryosurgical Ablation Of The Prostate, 72 Cancer 1291 (1993). In this procedure, generally referred to as cryoablation of the prostate, several cryosurgical probes are inserted through the skin in the perineal area (between the scrotum and the anus) which provides the easiest access to the prostate. The probes are pushed into the prostate gland through previously placed cannulas. Placement of the probes within the prostate gland is visualized with an ultrasound imaging probe placed in the rectum. The probes are quickly cooled to temperatures typically below xe2x88x92120xc2x0 C. The prostate tissue is killed by the freezing, and any tumor or cancer within the prostate is also killed. The body absorbs some of the dead tissue over a period of several weeks. However, other necrosed tissue may slough off and pass through the urethra, often causing undesirable blockage. Thus, it is often desirable to avoid cryoinjury to the urethra during cryoablation of the prostate. This may be done by placing a warming catheter in the urethra and continuously flushing the catheter with warm fluid to keep the urethra from freezing.
Devices for warming the urethra have been available for quite some time. In 1911, U.S. Pat. No. 1,011,606 issued for an xe2x80x9cAppliance For Subjecting Portions of The Human System To Heat Or Cold.xe2x80x9d This device was a coaxial dual lumen catheter intended for the application of therapeutic cooling or heating to the urethra and bladder. Devices for warming other body parts have also been proposed, such as Grams, Ear Probe For Use In Closed-Loop Caloric Irrigation, U.S. Pat. No. 4,244,377 (Jan. 13, 1981), which shows a coaxial dual lumen cannula intended for the application of therapeutic heating inside the ear. Baust, et al., Closed Circulation Tissue Warming Apparatus and Method of Using the Same in Prostate Surgery, U.S. Pat. No. 5,437,673 (Aug. 1, 1995), and related publications, illustrate use of a urethral warming catheter which is used to protect the urethra from cryothermal damage during cryosurgical treatment of the prostate for benign prostate hyperplasia. The Baust patent discloses a coaxial three lumen catheter in which warm saline passes through the outside lumen, returns through a coaxial second lumen, while the third lumen is a urinary drainage lumen centrally disposed within the other two lumens. The catheter is used to heat the urethra while the prostate is being frozen with cryosurgical probes.
Eshel, Technique for Localized Thermal Treatment of Mammals, U.S. Pat. No. 5,257,977 (Nov. 2, 1993) shows a catheter which delivers heated saline flow to provide therapeutic hyperthermia treatment of the prostate. Like the Baust patent, Eshel shows a three lumen catheter with centrally located urinary drainage lumen.
Still other devices have been described for importing fluid into the body and allowing a means for removing fluid from the body. One such device is described in Schossow, Endotracheal Tube, U.S. Pat. No. 3,087,493 (Apr. 27, 1960). Schossow describes a device employed to intubate the human trachea, such device connected with ducts and/or tubes outside the patient for the purpose of, for example, drawing off from the patient""s respiratory tract undesirable liquids and/or introducing beneficial liquids into the trachea. The device consists of an outer tube, which fits inside the patient""s trachea, and a two layered inner tube. The lumen of the inner tube is open to be connected with devices or ducts through which suction may be applied or fluids injected into the trachea. The distal portion of the inner tube is vented with ports or openings which create a xe2x80x9csprinklerxe2x80x9d effect inside the tube. Schossow does not suggest use as a urethral warming catheter during cryoablation of the prostate.
During cryoablation, the prostate tissue is killed by freezing temperatures in the cryogenic temperature range, typically xe2x88x92120xc2x0 C. and below. The hot fluid used for the warming catheter is supplied at about 30xc2x0 C. to 50xc2x0 C. Warm fluid is pumped through the urethral warming catheter, such as the catheter described in Baust. As the warm fluid travels the length of the urethral catheter disposed within the cryosurgically cooled urethra, it is cooled by the surrounding freezing tissue. By the time the hot water has traveled from the bladder neck sphincter to the external sphincter, it has been significantly cooled by the surrounding frozen prostate. As a result, the urethral tissue near the bladder neck sphincter (near the hot water outlet) is heated more than the urethral tissue near the external sphincter, creating a strong thermal gradient in the prostatic urethra and an uneven heating effect. By the time the hot water reaches the external sphincter, it may have lost so much heat to the upper region of the urethra that it is not warm enough to protect the external sphincter from freezing. In order for the tissue at the bladder neck sphincter to be adequately warmed, hotter water must be pumped in, risking urethral damage due to scalded tissue, or more water must be pumped at higher rates and pressures, increasing the material requirements of the hot water supply system and the warming catheter.
Another practical problem that arises in the current design of urethral warming catheters is that there is no provision for the use of a guide wire to assist in placement of the warming catheter. The warming catheter must be inserted into the urethra in order to protect the urethra during cryoablation. Insertion of the catheter may be difficult, especially if the urethra is blocked. This often occurs because the prostate is swollen, and the swollen prostate pinches the urethra shut, or because of some undesired tissue growth within the urethra which accompanies the underlying BPH or prostate cancer condition.
Yock, Angioplasty Apparatus Facilitating Rapid Exchange and Method, U.S. Pat. No. 5,501,227 (Mar. 26, 1996) describes an apparatus for inserting a balloon angioplasty catheter into a patient""s blood vessel. It consists of a balloon angioplasty catheter with a monorail or side saddle lumen placed distal to the angioplasty balloon. This lumen accepts a guide wire which may be threaded into the lumen. After the guide wire is placed in the blood vessel, the back end of guide wire is threaded into the monorail lumen, and the catheter is then pushed along the guide wire until it is in place within the blood vessel. Yock does not suggest use during cryoablation of the prostate or use within the urethra.
The devices described below provide an improved method and means for maintaining the temperature of urethral tissues during cryoablation of the prostate gland and thereby eliminates or reduces the sloughing of dead cells into the urethra. Diffuser holes or ports, much like a xe2x80x9csprinkler,xe2x80x9d are drilled into the inner tube of the warming catheter. The holes create an advantage over the prior art of achieving improved uniformity of fluid flow and temperature, utilizing a lower initial temperature and resulting in a more even application of thermal treatment to the urethral tissues. The apparatus may find additional utility in other areas of surgery where thermal treatment or maintenance of tissues is required with or without the capability of drainage.
The devices also provide an improved means for introducing the warming catheter into the human body. The device employs a monorail sleeve or guide-eye on the distal end of the catheter such that the proximal end of the guidewire can be slipped through the monorail sleeve of the catheter. The various configurations of the monorail sleeve and monorail tip may be employed to deliver the catheter.